The present invention relates to a sheet discharging apparatus, and more specifically, to an apparatus for discharging sheet stacks from a sorter connected with an image forming apparatus.
Japanese Patent Laying Open Gazette No. 231757/1989 discloses a sorter which includes a plurality of vertically movable bins storing sheet stacks discharged from a copying machine through a sorter inlet. A stapler is provided at the sorter inlet to staple sheet stacks in the bins.
However, since the sorter is not provided with a sheet discharging apparatus to discharge the sheet stacks from the bins, it is impossible to automatically finish all the required copies if the number of copies is larger than the number of the bins. Because, all the bins have been filled up with sheet stacks before the required number of copies are made. So, to finish a great number of copies, an operator must manually take out the stacks from the bins when the stacks fill up the bins.
Japanese Patent Laying Open Gazette No. 165270/1988 discloses a sorter connected with an image forming apparatus, in which a stapler is provided downward apart from a sorting unit and a unit for storing stapled stacks is disposed under the stapler. In the stapling operation, a stack of sheets once sorted by the sorting unit is transported to the stapler, where the stapler staples the fed stack and then discharges it into the lower storing unit. This apparatus can handle a number of sheet stacks to staple which is greater than the number of bins in the sorting unit.
However, the position of the stapler under the bins makes it difficult to remove the stapled stacks from the storing unit.
In order to overcome the problems of both antecedent sorters, the inventors of the present invention have developed a sorter having a sheet stack discharging apparatus which is provided in the front of the sorter. See U.S. co-pending application Ser. No. 08/053,952. The sorter can handle a number of sheet stacks greater than the number of bins, and it facilitates easy removal of stapled stacks from the sorter by providing the sheet stack discharging apparatus in the front of the sorter.
This sheet stack discharging apparatus has a hand mechanism for taking out the sheet stacks from the bins, and the hand mechanism is provided above a sheet transporting route, between the bins and the storing portion. The position of the hand mechanism makes the sheet stack discharging apparatus inconveniently tall.
This sorter has an opening on the front side, or operator side, of the sorter through which stapled stacks of sheets are removed from the sorter by the sheet stack discharging apparatus. The bins of the sorter stacked in the vertical direction are vertically moved by a mechanism which includes a pair of rotatable rods extending vertically and having a special helical groove on their surface.
The copying-machine-end of the bins engage the groove of the vertical rotable rods. Rotation of the rods move the bins up and down. There is a gap which is an opening between the bins and the stapler, and it is required to avoid interference with the driving mechanism, including the vertical rods, when the sheet stacks are removed by the hand mechanism of the sheet stack discharging apparatus. This space makes the sorter bulky.